Method of producing a medicinal mineral oil



United States Patent 3,980,313 METHOD OF PRODUCDIG A MEDICINAL MINERALOliL Kenneth M. Beals and William A. Home, 0ai rn0nt,-Pa., assignors toGulf Research & Development Company,

Pittsburgh, Pa., a corporation of Delaware No Drawing. Filed Nov. 24,1959, Ser. No. 855,014

1 Claim. (Cl. 2438-168) This invention relates to a method for makinghigh purity, light colored petroleum oils and to the novel products ofthe method. More particularly, it relates to a method comprisinghydrocracking of a residual crude oil fraction and to the novel'ligh'tcolored or colorless oil compositions consisting essentially ofnaphthenic hydrocarbons that are obtained thereby.

It is known in the art to prepare light colored or colorless lubricatingoil fractions by severely acid treating a straight run or partiallyrefined lubricating oil fraction. The light'col'ored or white oilproducts of conventional treatments have a low or negligible content ofaromatics;

They consist essentially of mixtures of paraffin and naphthenichydrocarbons and have about the same molecular weight range or boilingrange as the charge stock.

We have now developed a new method for producing light colored orcolorless lubricating oils of low viscosity from heavy residualpetroleum oil fractions. Our method unexpectedly producesoils of novelcomposition, specifically, oils that consist entirely or almost entirelyof naphthenic'hy'droc'arbons. These oils are substantially entirelylightcolored, low viscosity lubricating oils which have excellent viscosityindex-*an'd high specific gravity relating to-conven'tional highlyrefined white oils. They consist almost entirely of naphthenes, beingfree of or substantially free of aliphatic parafiins and having no morethan a low content of aromatics, e.g., less than 5 mol percent. Bydistillation and other refining treatments that characterize thepreferred form of our process they can be freed completely of aliphaticparafii'ns and arimatics and rendered colorless, tasteless and odorless.

Because of their unique composition and numerous valuable qualities, theoils of our invention are valuable for many uses and are uniquelyadapted for certain purposes. They are suitable'for pharmaceutical andcosmetic purposeswherein"the'oils are solvents or carrier media foractive pharamaceutical' or cosmetic ingredients. They are also usefulassolveuts or carriers for insecticides, their colorless quality makingthem free from harmful staining effects. Being colorless or lightcolored, the'light lubricating oils of the invention are'valuable aslubricants for textile and food machinery because they will notstain-the textile or food products. In these lubricating uses ourproducts are especially valuable because of their high viscosityindices.

Being almost entirely naphthenic, the oils of our inven- "ice tion havehigher'specific gravity than conventional white oils of similarmolecular weight range that contain large proportions of aliphaticparafiins. The higher specific gravity makes our oils superior forforming emulsions because, as recognized in the art,-the closer thedensity of an oil is to that of Water the more readily it forms a stableemulsion with water. To obtain satisfactory emulsions with conventionalwhite oils having a high content of open chain parafiins it hassometimes been necessary to include aromatics in the oil to raise thespecific gravity or to use an undesirably large amount of emulsifyingagent. However, aromatic are undesirable in cosmetic and pharmaceuticalproducts. Aromatics may be carcinogenic and also are generally morereactive than naphthenes and paraffin's. Thus, because of the highspecific gravity of the naphthenic oils of our invention, theyare'especially valuable for forming with Water stable emulsions to beused as cosmetic or pharmaceutical lotions, ointments or the like, thatare essentially free of carcinogenic or reactive aromatics.

Even when physiological eifects are not a problem, our

oils are especially valuable in forming emulsion lubricants because,being'naphthenic and thus of higher density than parafiinic oilsof thesame molecular weight range, they require smaller amounts of emulsifyingagents or othercontaminant's forforming a stable emulsion than lowerdensity paraffinic oils. In comparison to oils that are readilyemul-sifiable because of high density resulting from aromatics content,our oils are less subject to chemical deterioration. In 'fact, inall'of'the mentioned uses, stability against deterioration or chemicalchange is a valuable property of our naphthenic oils. Thischaracteristic is especiall'yimpo'rtan't for'lubricants such as textilemachinerylubricantswhich must not develop excessive colo'r'or acidity.

In general the method of our invention, by which our new products aremade, comprises subjecting to severe hydrocracking' a heavy residualcrude petroleum fraction by contacting the hydrocarbon charge with acatalyst comprising one 'or'm'or'e' sulfides of metals of group Via ofthe periodic table at a temperature from 700 to 800 F., a pressure above1,500- pounds per square inch gauge, a hydrogen to hydrocarbon'feedratio from 2,500 to 10,000 standard cubic feet per barrel of hydrocarbonand at a liquid-hourly space velocity from 01410 1.5 volumes per volumeper hour. 'Ih'e'hyd'rocracked' product is distilled to recover alightlubricating oil of which the initial boiling'point is"above400 F. and ofwhich the end point, or at least the'95 percent point, is lower than theinitial boiling point, or at least lower than the 5 percent point, ofthe hydrocracking charge, said oil containing less than about 5 molpercenta'liphatic paraffins and less than about 5 mol percent aromatics:In a preferred embodimentthe light lubricating oil'is distilled to aninitial boiling point that is sufiiciently high'that'theoikis free ofaliphatic parafrlns and the oil is clay contacted and acid-treated toobtain an oil that is also colorless and free of aromatics. In anotherpreferred embodiment, dewaxing'is used to obtain a product of low pourpoint.

The product of our invention'is the naphthenic light lubricating'oilobtained by the above method which is free of or substantially-free 0faliphatieparaffins, (i.e., contains less than about 5 mol percentaliphatic parafiius), contains less than 5 mol percent aromatics, hasa'viscosity index of at least 90, and preferably at least 100, and anASTM Union color lighter than 1.

The method and product of our invention are illustrated by the followingexample.

EXAMPLE 1 The charge stock was a deasphalted residual fraction ofOrdovician crude oil having the following characteristics:

Gravity, API 23.6

This heavy oil was charged to a hydrocracking reactor containing a fixedbed of pelleted catalyst composed of nickel and tungsten sulfides in amol ratio of 4:1. Reaction conditions included temperature of 745 to 775F., pressure of 3,530 pounds per square inch gauge, hydrogen rate of5,000 standard cubic feet per barrel of hydrocarbon and liquid-hourlyspace velocity of 0.5 volume of hydrocarbon per volui .e of catalyst perhour. The normally liquid product from the hydrocracking operation wassubjected to atmospheric distillation to remove light furnace oil,gasoline and lighter material. The remaining product was distilled in acontinuous vacuum column to obtain a fraction boiling between furnaceoil and 725 F. (corrected to atmospheric pressure). This fraction wasre-run in a true-boiling point still to remove light ends and an oil wasobtained having a viscosity at 100 F. of about 70 Saybolt Universalseconds. The oil was treated with fullers earth and filtered.Inspections of the product are as follows:

Table I Inspection data:

Gravity, APT 34.5 Specific gravity 0.8524 Viscosity, SUS:

100 F 69.6 210 F 36.6 Viscosity index 110 Color, Union: ASTM D155-45 1-Flash point, 0.C., F.: ASTM D92-52 390 Fire point, 0.0., F.: ASTM D92-52420 Pour point, F.: ASTM D97-47 30 Refractory index, 70 C. 1.4512Sulfur, percent 0.04 Nitrogen, percent 0.003 Carbon residue, Conradson,percent: ASTM D18952 0.01 Copper strip test, 212 F., 3 hrs.: ASTMD130-55T 1 Neutralization value, ASTM D974-54T: total acid No. 0.02Iodine No., mod. Hanus 3.5 Distillation, vacuum, corrected to 760 mm.

Over point F.) 455 at F.) 685 at F.) 696 50% at F.) 707 70% at F.) 71990% at F.) 733 Hydrocarbon type analysis by high temperature massspectrometer, rnol percent:

Alkanes 0.0 Non-condensed cyclo-alkanes 63.8 Condensed cyclo-alkanes33.1 Mono-nuclear aromatics 2.8 Naphthalenes 0.3

Table I shows that our product is an almost water-white, lubricatingoil. It is a light lubricating oil, having a Saybolt Universal viscosityat 100 F. in the range of 55 to seconds, and specifically of 69.6seconds in the example. It has a high viscosity index, i.e., above 90,and specifically the product of the example had a viscosity index of110. The distillation indicates that the oil is substantially entirely asynthetic, hydrocracked product since its distillation point issubstantially lower than the 10% distillation point of the residualcharge stock. The analysis shows that the oil is completely free ofparaffins and has a very low content of aromatics, namely, 2.8 percentmono-nuclear aromatics and 0.3 percent naphthalenes. The inspection datashow various valuable prcperties that are characteristic of the highpurity naphthenic product, the high specific gravity being especiallynotable.

The yields of different fractions of Example 1 give an indication of therelationship of our product of the residuum charged to hydrocracking. Inthe hydrocracking stage the yield of liquid product based on thehydrocracking residual charge stock was 104.6 volume percent. Afterremoval of light furnace oil and gasoline, the hydrocracked productamounted to 72.3 volume percent of the hydrocracking charge stock.Vacuum distillation of the latter product produced our product asdefined in Table I in a yield of 10.8 volume percent of the vacuum towercharge. In Example 1 there was also obtained from the heavy residualhydrocracking charge stock a good yield of furnace oil and of a highlynaphthenic gasoline that is an excellent reforming charge stock.

We have indicated that the starting material for our process is anasphalt-free or deasphalted crude oil residuum. The starting materialcan be any residuum obtained by vacuum or like distillation of any crudepetroleum or residual fraction thereof which, after (leas phalting, hasa viscosity at 210 F. of 90 to 200 Saybolt Universal seconds. Forinstance, the residuum can be prepared by vacuum distillation of aPennsylvania, Mid- Continent, West Texas, Kuwait, etc., crude. Anyconvcntional deasphalting procedure can be used. Preferably, theresiduum is deasphalted by contact with a low boiling hydrocarbon suchas propane, propylene or butane to precipitate asphalt which is thenseparated from the oil.

To hydrocrack the deasphalted residuum we employ a solid catalyst whichnot only has high activity for saturation of aromatics but also highactivity and selectivity for carbon-carbon bond scission. Suchhydrocracking catalysts are known in the art. They comprise the sulfidesof metals of group We of the periodic table mixed with a sulfide of aniron group metal. The sulfide catalysts can initially be in the oxideform and converted to sulfides in the reaction zone by reaction withsulfur in the charge stock or with a sulfur compound such as hydrogensulfide that is introduced into the reactor to sulfide the catalyst.Specific catalysts can consist of molybdenum sulfide, tungsten sulfideor chromium sulfide mixed with a sulfide of iron, cobalt and/ or nickel.A particularly desirable catalyst is a mixture of nickel sulfide andtungsten sulfide. Such a catalyst containing from 1 to 4 mole of nickelper mol of tungsten (calculated as metals) has especially high activityand selectivity for hydrocracking. Other satisfactory sulfide mixturesare cobalt sulfide-tungsten sulfide and nickel sulfide-molybdenumsulfide mixtures. The catalysts can be supported or unsupported.

The hydrocracking reaction conditions for our process are of suchseverity as to produce an entirely synthetic light lubricating oilproduct. The temperature can range from 700 to 800 F. and temperaturesof 725 to 775 F. are preferred. The pressure should be above 1,500pounds per square inch gauge. There is no upper limit on pressure but apressure in the range of 2,000 to 4,000 pounds per square inch gauge ispreferred because of the excessive cost of equipment required for higherpressures. A relatively low liquid-hourly space velocity is employedsons to obtain severe hydrocracking. A suitable range,

for the space velocity is 0.4 to 1.5 volumes of liquid hydrocarbon pervolume of catalyst per hour.

The hydrogen employed in the process can be pure hydrogen but hydrogenof lower purity such as a reformer hydrogen stream containing about 80mol percent hydrogen works very well. If an impure hydrogen stream isused, it is recommended that part ofthe recycle hydro gen be bled fromthe recyclestream or that a recyclehydrogen clean-up procedure be used.The hydrogen-tohydrocarbon ratio of the reactor charge, includingrecycle and fresh hydrogen, should be from about 2,500 to 10,000standard cubic feet per barrel'of hydrocarbon charge.

The efiiuent from thehydrocracker is normally subjected to cooling andgas-liquid separation to separate hydrogen and other light gases fromthe normally liquid hydrocarbons. The hydrogen-rich stream recovered inthis manner can be recycled to the hydrocracking reaction.

The next step in the process, namely, dis-tillation of normally liquidhydrocarbons of the hydrocracking efiiuent, is of critical importance inour process. The liquidef fluent from the hydrocracking stage has afullboiling range from gasoline to heavy lubricating oil and containsparaflin wax. The product'of our invention is recovered from this liquidby distillation. The gasoline and light furnace oil can be distilled offat atmospheric pressure but, in order to prevent decomposition of theheavier fractions, our light'lub'ricating oil fraction is-recovered byvacuum distillation. The product of the invention is recovered as adistillate fraction having an initial boiling point above 400 F. and a95% point below 950 F., all temperatures being corrected to atmosphericpressure. Our preferred product, as shown in the example, is thedistillate fraction of the liquid hydrocracking efiiuent having aninitial boiling point above 450 F. and a 90% point below 750 F.

Although our procedure of severe hydrocracking of selected stocks andselective distillation of the product thereof will produce a novel andvaluable light colored light lubricating oil without further treatment,we prefer, as indicated in the example, to subject the light lubricatingoil distillate to clay contacting. This can be carried out in accordancewith known procedure wherein the oil is mixed with powdered filter claysuch as fullers earth. The oil-clay slurry is held at elevatedtemperature, e.g., 200 to 600 F. for several minutes and is then pumpedthrough a filter press to separate the clay from the oil. The mainresult of this procedure is further to decolorize the oil, although evenwithout the clay contacting step our product is substantially colorlessor of very light color.

As shown in Table I the product of our process, although free ofparaiiins, may have a small content of aromatics, i.e., less than aboutmol percent. To obtain a completely naphthenic white oil that iscompletely colorless, tasteless and odorless, we can subject thehydrocracked light lubricating oil of the invention to conventional acidtreating. A suitable acid treating procedure involves contacting the oilin a series of batch treatments with small amounts of sulfuric acid(e.g., 5 Weight percent of the oil) using 20 percent oleum (104-105percent H 80 for each treating shot. After contaeting with the acid thesulfonate sludge is settled, the oil is decanted and the procedure isrepeated several times. Preferably, the oil is then neutralized bywashing with a solution of a basic substance, e.g., sodium carbonatesolution, The washed neutral oil is air dried and is then filtered withadsorbent clay. Our product of Table I has been subjected to sulfuricacid treatment substantially in the manner described with the followingresults.

Acid Treatment: I Acid cdnsumemwr. percent 2,0.0 Whiteoilyield',vo1.percent 94,0 Sulffonate yield, v01; percent; 1:0

Table: II shows-that'sulfuric acid treatment of 1 the productof TableI-resulted in-a'white oil yield of 94' volume percent with a ratherlowacid consumption. The prod-' uct istastele'ss, odorless, colorless:and-is substantially-en tirely naphthenic, the small content ofaromaticshaving' been removed by the acid'treatment; The cloud and pour;points'of the acid treatedoil are entirely: satisfactory. for'many'purposes'but are rather high for some purposes; The rather highvalues are probably the result of certain high meltingpoint naphthenichydrocarbons being present intheoil. The cloudandpour points can belowered by subjecting the oil to conventional dewaxing. procedures; Forcertain lubricatingspurposes for which low. pour pointis desired thepour point can also"bereduce'd by adding a small amount of anyconventional pour point de-' pressant such as Acryloid 618 which is a"polymethacrylate.

' EXAMPLES 2 AND 3 In other operations in which the deasphaltedOrdovician residual fraction described in Example 1 was hydrocrackedsubstantially in the manner of Example 1 we have used dewaxing in theproduct recovery procedure to obtain products of low pour point. Inthese runs the hydrocracking efiluent was subjected to gas separationand the liquid hydrocracking product was subjected to atmosphericdistillation with steam stripping to remove light furnace oil, gasolineand lighter products. The remaining product was then subjected tosolvent dewaxing with methy-l ethyl ketone and employing a rotaryfilter, the dewaxing conditions being such as to produce the desiredpour point for the ultimate product. In Example 2 the dewaxed productwas subjected to continuous vacuum distillation and in Example 3 wassubjected to precise, batch, vacuum distillation, in each instance torecover a light lubricating oil having substantially the composition ofthe products of the invention. The properties of the light lubricatingoil fractions obtained as products of these two runs are listed in TableIII.

Table III Inspection Date Example Example Gravity, API 30.4 35.7Specific Gravity..- 0. 8428 5 viscpggy, SUS- O 8 63 58. 9 62.0 210 35. 035. 6 Viscosity Index 104 113 Pour Points, F.; AS'IM D9747 -30 5 Sulfur,percent 0.04 0. 04 Iodine No., Mod. Hauus 4.1 Color, Union, ASTM D155-41- Carbon Residue, Conradson, percent ASTM D189 52 0.01 NeutralizationValue, ASTM D974-54Tz Total Acid l To 0.01 Distillation, Vacuum,Corrected to 760 mm. Hg:

Over Point (F.) 441 at (F.) 714 Hydrocarbon Type Analysis by HighTempereture Mass Spectrometer, M01 percent:

Alkanes 3. 2 1. 3 Non-condensed cyclosalkaues 08. 8 70.1 Condensedcyclo-alkanes 25.6 25. 3 Mono-nuclear aromatics..- 2. 2 3. 1Naphthalenes 0. 2 0. 2

The above table shows that conventional dewaxing can be used to produceproducts of the invention of low pour point, for example, 30 F. inExample 2 and F. in Example 3. The products of these examples had asmall content of alkanes but can be rendered essentially free of alkanesif distilled to a somewhat higher initial boiling point or percentpoint, the reason being that the alkanes are in the light end of theproduct. The preferred products of our invention are essentially free ofopen chain parafins, as in Example 1, but products such as Examples 2and 3 which have a small content of alkanes, e.g., less than about 5 molpercent, have many of the valuable properties that characterize theproducts of the invention. Thus, the products of Examples 2 and 3 havehigh specific gravity, high viscosity, index, light color and arecomposed almost entirely of naphthenic hydrocarbons. They also have goodstability. The product of Example 3 was maintained at 210 F. for 48hours and no color change was observed. The product did form a smallprecipitate when exposed to light for 4 days, but a similar productwhich had been clay treated did not change after 30 days exposure tolight.

Obviously many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof and therefore only such limitations should be imposed asare indicated in the appended claim.

We claim:

A method for producing light colored medicinal mineral oil whichcomprises contacting a deasphaltcd residual petroleum crude oil fractionhaving a viscosity at 210 F. or at least 90 SUS with a hydrocrackingcatalyst comprising a sulfide of a group VIa metal and a sulfide of aniron group metal in the presence of hydrogen under severe hydrocrackingconditions, said conditions including a temperature from 700 to 800 F.,a pressure above 1,500 pounds per square inch gauge, a hydrogenconcentration from 2,500 to 10,000 standard cubic feet per barrel ofhydrocarbon and a liquid-hourly space velocity from 0.4 to 1.5 volumesof liquid hydrocarbon per volume of catalyst per hour, fractionallydistilling the liquid hydrocarbon product from this hydrocrackingoperation, separating a distillate fraction which consists essentiallyof naphthenic hydrocarbons and less than 5 mol percent each of aliphaticand aromatic hydrocarbons, which fraction has a viscosity at 100 F. ofbetween about and SUS, which fraction has a viscosity index of at least90, which fraction has an initial boiling point above about 450 F., andwhich fraction has a percent boiling point below about 750 F. andsubjecting said fraction to acid and clay treatment.

References Cited in the file of this patent UNITED STATES PATENTS2,554,282 Voorhies May 22, 1951 2,882,220 Mikeska et al. Apr. 14, 19592,899,380 Lanning Aug. 11, 1959 2,934,492 Hemminger et al Apr. 26, 19602,967,204 Beuther et a1. Jan. 3, 1961 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION 3 Patent No, 3,080,313 March 5, 1963 KennethM, Beals et a1,

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 1, line 48, for "arima'tics" read aromatics column 2, line 12,for "aromatic" read aromatics column 3, line 51, for "Refractory" readRefractive column 4, line 18, for ."of", third occurrence, read tocolumn 6, Table III, third column, line 2 thereof, for

O,856,8" read 0,8463 column 7, line 15, after "viscosity" strike out thecomma;

Signed and sealed this 8th day of October 1963.,

(SEAL) Attest:

EDWlN L, REYNOLDS ERNEST w. SWIDER Attesting Officer Act ingCommissioner of Patents

